Assessment versions

Published (reviewed and quality assured)

Justification for indicator selection

Populations typically have an optimum temperature at which the (daily or weekly) death rate is lowest. Mortality rates rise at temperatures outside this comfort zone. Figure 1 shows a typical U/J-shaped relation (in 15 European cities assessed in the PHEWE project). The trough represents the comfort zone; the steeper (right) arm of each line shows the mortality increase at high temperatures, and the left arm of each line shows the increase at low temperatures. Overall, the impact of hot weather and heat waves depends on the level of exposure, the size and structure of the exposed population, the population sensitivity, the preparedness of health systems, and the prevention measures in place. In temperate countries, there is a seasonal variation of mortality, with higher mortality in winter than in summer. There is uncertainty on whether some current observed reductions in winter mortality can be attributed to climate change (Confalonieri et al., 2007). People with cardiovascular diseases are more at risk in winter, because of the cold-induced tendency of blood to clot. Heat waves have caused significant mortality in Europe in recent decades. However it is difficult to compare the heat-wave effects across Europe and over time. Heat directly affects the human physiology: thermoregulation during heat stress requires a healthy cardiovascular system. When environmental heat overwhelms the heat-coping mechanism, the body's core temperature increases. This can lead to heat illness, or death from heat stroke, heart failure and many other causes.Several medical factors can increase the risk of heat-wave mortality, including dehydration, drugs, ageing, and having a chronic disease that affects cardiac output and skin blood flow, as well as being confined to bed. Social factors, such as social isolation, may also be important, although there has been little research in Europe (Bouchama, 2007). Many housing and urban factors have also been assessed, in particular for their role in high indoor temperatures (Kovats and Hajat, 2008). One special concern relates to indoor temperatures in health-care facilities and nursing homes. Increasing numbers of older adults in the population will increase the proportion of the population at risk (Confalonieri et al., 2007). Health-system action will be needed to ensure adequate planning of locations for health care and nursing institutions, as well as for the thermal protection of their facilities. The EuroHEAT project concluded that heat-related illnesses and deaths are largely preventable. In the long term, the most important measure is improving urban planning and architecture, and energy and transport policies. Such improvements should begin now, as the lead time for policy development is very long. Heat-wave effects can be reduced by keeping indoor temperatures low, keeping out of the heat, keeping the body cool and hydrated, and helping others. Health-system preparedness planning is essential, by collaborating with weather services in providing accurate, timely weather-related health alerts and developing strategies to reduce individual and community exposures to heat, especially among vulnerable populations, planning health and social services and infrastructure, and providing timely information to the population (Matthies et al., 2008).

Scientific references:

No rationale references
available

Indicator definition

Daily mortality rates in 15 European cities by apparent temperature in summer time

Units

Policy context and targets

Context description

In April 2009 the European Commission presented a White Paper on the framework for adaptation policies and measures to reduce the European Union's vulnerability to the impacts of climate change. The aim is to increase the resilience to climate change of health, property and the productive functions of land, inter alia by improving the management of water resources and ecosystems. More knowledge is needed on climate impact and vulnerability but a considerable amount of information and research already exists which can be shared better through a proposed Clearing House Mechanism. The White Paper stresses the need to mainstream adaptation into existing and new EU policies. A number of Member States have already taken action and several have prepared national adaptation plans. The EU is also developing actions to enhance and finance adaptation in developing countries as part of a new post-2012 global climate agreement expected in Copenhagen (Dec. 2009). For more information see: http://ec.europa.eu/environment/climat/adaptation/index_en.htm